package com.astersoft.lib.text;

/*
 * Copyright 2012 AsterSoft personal developer - Licensed under the Apache
 * License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law
 * or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

/**
 * Provides a method to encode any string into a URL-safe
 * form.
 * Non-ASCII characters are first encoded as sequences of
 * two or three bytes, using the UTF-8 algorithm, before being
 * encoded as %HH escapes.
 *
 * Created: 17 April 1997
 * Author: Bert Bos <bert@w3.org>
 *
 * URLUTF8Encoder: http://www.w3.org/International/URLUTF8Encoder.java
 *
 * Copyright © 1997 World Wide Web Consortium, (Massachusetts
 * Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. 
 * This work is distributed under the W3C® Software License [1] in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 * 
 * This class was extended by dario durzo
 * 
 */
public class ASURLUTF8Utils
{

	final static String[] hex = {
		"%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07",
		"%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f",
		"%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17",
		"%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f",
		"%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27",
		"%28", "%29", "%2a", "%2b", "%2c", "%2d", "%2e", "%2f",
		"%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37",
		"%38", "%39", "%3a", "%3b", "%3c", "%3d", "%3e", "%3f",
		"%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47",
		"%48", "%49", "%4a", "%4b", "%4c", "%4d", "%4e", "%4f",
		"%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57",
		"%58", "%59", "%5a", "%5b", "%5c", "%5d", "%5e", "%5f",
		"%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67",
		"%68", "%69", "%6a", "%6b", "%6c", "%6d", "%6e", "%6f",
		"%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77",
		"%78", "%79", "%7a", "%7b", "%7c", "%7d", "%7e", "%7f",
		"%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87",
		"%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f",
		"%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97",
		"%98", "%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f",
		"%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7",
		"%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af",
		"%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7",
		"%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf",
		"%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7",
		"%c8", "%c9", "%ca", "%cb", "%cc", "%cd", "%ce", "%cf",
		"%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7",
		"%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df",
		"%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7",
		"%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef",
		"%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7",
		"%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff"
	};

	/**
	 * Encode a string to the "x-www-form-urlencoded" form, enhanced
	 * with the UTF-8-in-URL proposal. This is what happens:
	 *
	 * <ul>
	 * <li><p>The ASCII characters 'a' through 'z', 'A' through 'Z',
	 *        and '0' through '9' remain the same.
	 *
	 * <li><p>The unreserved characters - _ . ! ~ * ' ( ) remain the same.
	 *
	 * <li><p>The space character ' ' is converted into a plus sign '+'.
	 *
	 * <li><p>All other ASCII characters are converted into the
	 *        3-character string "%xy", where xy is
	 *        the two-digit hexadecimal representation of the character
	 *        code
	 *
	 * <li><p>All non-ASCII characters are encoded in two steps: first
	 *        to a sequence of 2 or 3 bytes, using the UTF-8 algorithm;
	 *        secondly each of these bytes is encoded as "%xx".
	 * </ul>
	 *
	 * @param s The string to be encoded
	 * @return The encoded string
	 */
	public static String encode(String s)
	{
		StringBuffer sbuf = new StringBuffer();
		int len = s.length();
		for (int i = 0; i < len; i++) {
			int ch = s.charAt(i);
			if ('A' <= ch && ch <= 'Z') {		// 'A'..'Z'
				sbuf.append((char)ch);
			} else if ('a' <= ch && ch <= 'z') {	// 'a'..'z'
				sbuf.append((char)ch);
			} else if ('0' <= ch && ch <= '9') {	// '0'..'9'
				sbuf.append((char)ch);
			} else if (ch == ' ') {			// space
				sbuf.append('+');
			} else if (ch == '-' || ch == '_'		// unreserved
					|| ch == '.' || ch == '!'
					|| ch == '~' || ch == '*'
					|| ch == '\'' || ch == '('
					|| ch == ')') {
				sbuf.append((char)ch);
			} else if (ch <= 0x007f) {		// other ASCII
				sbuf.append(hex[ch]);
			} else if (ch <= 0x07FF) {		// non-ASCII <= 0x7FF
				sbuf.append(hex[0xc0 | (ch >> 6)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			} else {					// 0x7FF < ch <= 0xFFFF
				sbuf.append(hex[0xe0 | (ch >> 12)]);
				sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]);
				sbuf.append(hex[0x80 | (ch & 0x3F)]);
			}
		}
		return sbuf.toString();
	}

	/**
	 * Decode a string from the "x-www-form-urlencoded" form, enhanced
	 * with the UTF-8-in-URL proposal.
	 * 
	 * @param s
	 * 		The encoded UTF-8 String
	 * @return
	 * 		The decoded String
	 */
	public static String decode(String s) {
		StringBuffer sbuf = new StringBuffer () ;
		int l  = s.length() ;
		int ch = -1 ;
		int b, sumb = 0;
		for (int i = 0, more = -1 ; i < l ; i++) {
			/* Get next byte b from URL segment s */
			switch (ch = s.charAt(i)) {
			case '%':
				ch = s.charAt (++i) ;
				int hb = (Character.isDigit ((char) ch) 
						? ch - '0'
								: 10+Character.toLowerCase((char) ch) - 'a') & 0xF ;
				ch = s.charAt (++i) ;
				int lb = (Character.isDigit ((char) ch) 
						? ch - '0'
								: 10+Character.toLowerCase((char) ch) - 'a') & 0xF ;
				b = (hb << 4) | lb ;
				break ;
			case '+':
				b = ' ' ;
				break ;
			default:
				b = ch ;
			}
			/* Decode byte b as UTF-8, sumb collects incomplete chars */
			if ((b & 0xc0) == 0x80) {			// 10xxxxxx (continuation byte)
				sumb = (sumb << 6) | (b & 0x3f) ;	// Add 6 bits to sumb
				if (--more == 0) sbuf.append((char) sumb) ; // Add char to sbuf
			} else if ((b & 0x80) == 0x00) {		// 0xxxxxxx (yields 7 bits)
				sbuf.append((char) b) ;			// Store in sbuf
			} else if ((b & 0xe0) == 0xc0) {		// 110xxxxx (yields 5 bits)
				sumb = b & 0x1f;
				more = 1;				// Expect 1 more byte
			} else if ((b & 0xf0) == 0xe0) {		// 1110xxxx (yields 4 bits)
				sumb = b & 0x0f;
				more = 2;				// Expect 2 more bytes
			} else if ((b & 0xf8) == 0xf0) {		// 11110xxx (yields 3 bits)
				sumb = b & 0x07;
				more = 3;				// Expect 3 more bytes
			} else if ((b & 0xfc) == 0xf8) {		// 111110xx (yields 2 bits)
				sumb = b & 0x03;
				more = 4;				// Expect 4 more bytes
			} else /*if ((b & 0xfe) == 0xfc)*/ {	// 1111110x (yields 1 bit)
				sumb = b & 0x01;
				more = 5;				// Expect 5 more bytes
			}
			/* No need to test if the UTF-8 encoding is well-formed */
		}
		return sbuf.toString() ;
	}

}
